how can i clear the error, Index exceeds the number of array elements. Index must not exceed 10. line (s1(i) = XSteamUS('​s_pT',p_in​let(i),t_i​nlet(i));)

offset_t = 50; % 50degC interval
offset_c = 1; % 1 psi interval

cp_low = 1;    
cp_high = 15; % Condenser Pressure Range
nstep_cp = 14;
delta_cp = (cp_high-cp_low)/nstep_cp;

tt_low = 700; 
tt_high = 1200; % Turbine Inlet Temperature Range
nstep_tt = 10;
delta_tt = (tt_high-tt_low)/nstep_tt;

tp_low = 2000;  
tp_high = 3000; % Turbine Inlet Pressure Range
nstep_tp = 20;
delta_tp = (tp_high-tp_low)/nstep_tp;

nstep_rhp = 16;
rh_ratio_high = 0.9; % Pressure Ratio 
rh_ratio_low = 0.1;
delta_rhp = (rh_ratio_high-rh_ratio_low)/nstep_rhp;

for i = 1:nstep_tt    % Turbine Temp (700-1200degC)
    t_inlet(i) = t1 + (i-1)*delta_tt;
end

for i = 1:nstep_tp   
    p_inlet(i) = p1 + (i+1) * delta_tp;  % Turbine Inlet Pressure 
    s1(i) = XSteamUS('s_pT',p_inlet(i),t_inlet(i));
    s2(i) = s1(i);
    rhp = p_inlet * delta_rhp;
    t2(i) = XSteamUS('T_ps',p_inlet(i),s2(i));
    h2(i) = XSteamUS('h_ps',rhp(i),s2(i));

Answer 1

[Walter Roberson]

for i = 1:nstep_tt    % Turbine Temp (700-1200degC)

nstep_tt is not defined in the code you posted. We have no reason to expect it is the same as nstep_tp that you do define.

[Julio Almanzar]

Missed that line of code during transfer. The correct code is up now!

[Walter Roberson]

nstep_tt = 10;
%...
for i = 1:nstep_tt    % Turbine Temp (700-1200degC)
    t_inlet(i) = t1 + (i-1)*delta_tt;
end

t_inlet is not pre-allocated, so the output size it will have after the loop corresponds to the maximum indexed assigned to, which is max(1:nstep_tt) which is floor(nstep_tt) which is 10. After that loop, up to t_inlet(10) will be assigned to and t_inlet(11) onwards do not exist.

nstep_tp = 20;
%...
for i = 1:nstep_tp   
    p_inlet(i) = p1 + (i+1) * delta_tp;  % Turbine Inlet Pressure 
    s1(i) = XSteamUS('s_pT',p_inlet(i),t_inlet(i));

nstep_tp is 20. When i reaches 11 in this loop, the assignment to s1(i) would effectively be

   s1(11) = XSteamUS('s_pT',p_inlet(11),t_inlet(11)); 

but only up to t_inlet(10) was created.